The brain is particularly rich in EFAs, but the parent dietary EFAs, namely linoleic acid and alpahlinolenic acid, are present only in small amounts. These dietary EFAs must be metabolised by the enzyme delta-6-desaturase (D6D), to give (from linoleic acid) gamma-linolenic acid (GLA) and (from alpha-linolenic acid) stearidonic acid 18:4 n-3, and then to other metabolites. Because ageing, alcohol, catecholamines released during stress, and lack of certain nutritional factors have all been shown to impair D6D function, it occurred to us to see if there was a particular value for the brain in administering GLA, 18:4 n-3 and the higher acids formed from them.